The present invention concerns a torsional vibration damper having a hub part (primary mass) which may be attached to a drive shaft of a motor, and an inertia ring (secondary mass) which encloses the hub part in the radially outer region, wherein a fluid-filled gap and a sealing device to prevent the escape of fluid are provided between the hub part and the inertia ring.
A torsional vibration damper of the generic type is known for example from GB 11 05 292 A.
In general, the torsional vibration dampers discussed here have an outwardly offset inertia ring, in contrast to the also known design in which the inertia ring is mounted fully encapsulated in a separate housing.
The disadvantage of the latter design is that the housing mass is irrelevant to the function of the damper and the heat dissipation is limited by the encapsulation of the inertia ring.
In the known torsional vibration dampers with outwardly offset inertia ring, it must be ensured that the escape of fluid present between the hub part and the inertia ring is avoided.
In the torsional vibration damper of the generic type, sliding sealing rings are used as seals, which has the disadvantage that a fluid, in particular silicon oil, is used as a damping medium but has no lubricating properties, so sliding seals are of limited suitability for solving the sealing problem since they suffer from high wear within a very short time. Furthermore, sliding seals do not guarantee complete protection against penetration of very small particles and e.g. water.
The present invention is based on the object of providing a torsional vibration damper of the generic type with sealing devices which do not have the above-mentioned disadvantages and which have a long service life.
This object is achieved in that the sealing devices each have a first ring tightly connected to the hub part and a second ring tightly connected to the inertia ring, and an elastomer ring which is connected sealingly on one side to the first ring and on the other side to the second ring.
Such a design avoids the disadvantages of the prior art since no friction can occur between the sealing elements and the rotating parts of the torsional vibration damper.
The first and second rings of the sealing devices which are sealingly connected to the hub part and to the inertia ring respectively are preferably made of metal.
Preferably, the respective elastomer ring of a sealing device is connected sealingly, by means of a rubber-metal connection produced during an elastomer cross-linking process, to the metal rings which are attached respectively to the hub part and to the inertia ring.
Preferably, as an elastomer between the respective first and second rings of a sealing device, a high-temperature-resistant elastomer is used such as e.g. EPDM or silicone material. The term “silicone material” in the context of this publication means a material which contains or is a synthetic polymer in which silicon atoms are linked via oxygen atoms.
This is particularly useful since said materials are also suitable for use in high temperatures.
The respective sealing devices are not by design sliding seals, so that a secure and permanent complete seal is achieved.
The sealing devices need not be pressed in, giving the advantage that the sealing devices may be fitted stress-free. Thus a defined state of the gap in the torsional vibration damper may be guaranteed, in particular if the inertia ring is mounted on plain bearings relative to the hub part.
It is possible that the at least one elastomer ring, preferably made of silicone material, is connected sealingly to superficial regions of the first and second rings which extend obliquely and/or axially and/or radially. “Obliquely” means at an angle relative to the axial direction and radial direction.
It is particularly advantageous if the at least one elastomer ring, preferably made of silicone material, is connected sealingly to differently oriented, in particular axially and radially extending, superficial regions of the one or two metal rings. Such a sealing connection in two directions on the primary mass and/or the secondary mass forms a particularly secure and durable connection. This may also guarantee a particularly well-defined state of the gap in permanent use.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.